Step 2: Use the z-table to find the percentage that corresponds to the z-score. Next, we will look up the value -0.2 in the z-table: We see that 42.07% of values fall below a z-score of -0.2. However, in this example we want to know what percentage of values are greater than -0.2, which we can find by using the formula 100% – 42.07% = 57.93%.
First, look at the left side column of the z-table to find the value corresponding to one decimal place of the z-score. In this case, it is 1.0. Then, we look up the remaining number across the table (on the top), which is 0.09 in our example. Using a z-score table to calculate the proportion (%) of the SND to the left of the z-score.A z z -score is a standardized version of a raw score ( x x) that gives information about the rel ative location of that score within its distribution. The formula for converting a raw score from a sample into a z z -score is: z = x −X¯¯¯¯ s z = x − X ¯ s. As you can see, z z -scores combine information about where the distribution is
Calculate Z Score and probability using SPSS and Excel. SPSS Excel one sample T Test. Calculate probability of a range using Z Score. Assume that a random variable is a normally distributed (a normal curve), given that we have the standard deviation and mean, we can find the probability that a certain value range would occur. Method 1: Use AVERAGE and STDEV.P Functions. If we calculate Z Score manually, we use the below formula. Z score = (X-μ)/σ = (target value - population mean) / population standard deviation. Follow the Z score formula with the help of Average Function to calculate mean and use STEDEV.P to calculate the population standard deviation. Step 3: Find the p-value of the z-test statistic using Excel. To find the p-value for z = 2.5, we will use the following formula in Excel: =1 – NORM.DIST (2.5, 0, 1, TRUE) This tells us that the one-sided p-value is .00621, but since we’re conducting a two-tailed test we need to multiply this value by 2, so the p-value will be .00612 * 2 w7Y0rp.